Print timing and speed control circuit for high-speed printers

ABSTRACT

A high-speed &#39;&#39;&#39;&#39;on-the-fly&#39;&#39;&#39;&#39; printer, wherein timing means is provided to identify the position of the print characters on a movable type-carrying member, to denote the instant for actuation of the print operation, and to control the speed of the motor driving the type-carrying member.

United States Patent Bonzano 1 1 Jan. 25, 1972 1541 PRINT TIMING ANDSPEED CONTROL 2,936,704 5/1960 Hense ..101/93 c T I 2,940,385 6/1960House 101/93 C CIRCUI FOR H GH SPEED PRINTERS 3,049,990 8/1962 Brown eta1. 101/93 C [72] Inventor: Giorgio Bonzano, Caluso, Italy 3,1 17,514 1/1964 Doersam 101/93 C 3,356,921 12/1967 Bradford 6! a1 318/341 X [73]Assgnee' g'z sysems 3,399,753 9/1968 Revelle ..197 49 a 3,472,35210/1969 Kondur 197/49 [22] Filed: June 25, 1970 3,559,017 1/1971Dinger..... 318/341 X 3,560,827 2 1971 8 M1 ..318 341 211 Appl. 196.;49,637 c er Primary Examiner-William B. Penn [3()] Foreign Applicationpriority m AttorneyGeorge V. Eltgroth, Lewis P. Elbinger, Frank L.

Neuhauser, Oscar B. Waddell and Joseph B. Forman June 28, 1969 Italy..18919 A/69 [57] ABSTRACT [52] US. Cl ..101/93, 197/16 51 1m.C1. ..B4lj,13411 1100 A high-Speed y" Primer, wherein liming means 15 [58] Field61 Search ..101/93 c; 197 1,49, 52, 16, Provided to identify thePosition of the Print characters on a 97 7 23 5; |73/28, 32 3 3 movabletype-carrying member, to denote the instant for ac- 318/34| tuation ofthe print operation, and to control the speed of the motor driving thetype-carrying member. [56] References cued 10 Claims, 4 Drawing FiguresUNlTED STATES PATENTS 2,915,966 12/1959 Jacoby ..101/93 C EEBNTING 85i?9 4 5 5 1116 F5 I 11 1 1 1 1 I g I 1 I b 1 1 14 1 I C 22 1:121 I I 15 16d 1 1 2i 7 1 POWER J REGULATINGV' CIROUI SUPPLY cmcun 5 PATENTED m2 I972MI a of 2 3.636. 867

Giorgio BO/VZANO INVEN'I'OR.

PRINT TIMING AND SPEED CONTROL CIRCUIT FOR HIGH-SPEED PRINTERSBACKGROUND OF THE INVENTION The present invention relates to high-speedprinters employed in digital data-processing systems, and moreparticularly to timing devices for use in such printers.

In the field of electronic data-processing devices, high printing speedsare obtained by the use of printers operating according to the principletermed on-the-fly" printing. Printers operating pursuant to suchprinciple may assume various forms, including serial printers,serial-parallel printers, chain or drum printers, etc. Printers of thistype employ impact printing or nonimpact printing, the latter includingelectrostatic and optical printing.

Briefly, because on-the-fly printers are well described in the priorart, these printers are characterized by a common element, i.e., atype-carrying member in continuous and uniform motion. The object of thetype-carrying member is to bring all characters, of the character setcarried by the member, sequentially into correspondence with one or morepredetermined printing positions, whereupon, at the proper moments, thedesired characters will be printed without halting the typecarryingmember.

These on-the-fly printers present the requirement for identifying thecharacters and the position they occupy at each instant. Usually theproblem is solved by providing a timing member, comprising acode-carrying device, moving integrally with the type-carrying memberand bearing one or more readily recognizable reference and timing marks,located at positions corresponding to the positions of the differentcharacters on the type-carrying member.

Various types of timing devices may be used for this purpose, such asthose using photoelectric, magnetic, or capacitive pickup techniques.Difi'erent character-identifying techniques may be used, such as thedirect comparison, of hinary codes or the stepping of codes throughpulse counting.

An example of such techniques is provided in the Italian patentapplication N. 17,563 A/69 filed May 30, 1969 and the corresponding US.patent application Ser. No. 42,438, filed June 1, 1970, by F. Castoldifor SINGLE PICK-UP TIMING DEVICE FOR HIGH-SPEED PRINTER, both suchapplications being assigned to the assignee of the instant invention. Acommon characteristic of all of these techniques is to provideidentifying timing pulses which recur uniformly so that not only can thecharacters to be printed be identified, but also so that the printingoperating can be synchronized by means of these pulses, i.e., thesepulses are employed to determine the times at which the printing membermust be actuated to effect the printing operation.

If the logical operations of identifying a character and actuating theprinting member required no time lapse, the timing pulses could beprecisely concurrent with the times at which the various characters arein correspondence with a printing position. In such instance the speedwith which the characters reached the printing position would notinterfere with the proper printing operation. Practically, however, thetiming pulses must be suitably advanced with respect to the times atwhich the characters to be printed are in correspondence with a printingposition; for example, this lead time may be of the order ofmilliseconds.

As such lead time is obtained by appropriately offsetting the timingmember with respect to the type-carrying member by a suitable angle, itis manifest that the speed of the type-carrying element must bemaintained between precisely determined limits to ensure correctprinting. The required speed control is generally obtained by the use ofsmall-slip asynchronous motors. The synchronous speed of these motorsdepends, as is use in different countries (25 or 50 Hz., instead of thestandard 60 Hz.) pose additional problems. Since the printers usingthese motors are also provided with electronic circuits, which require adirect current supply, it would be desirable to also use DC motors fordriving the type and code-carrying members. However, the use of DCmotors normally requires sophisticated speed regulation circuits, whichcomprise tachometric generators, difference amplifiers, and otherdevices.

Therefore, it is the object of this invention to eliminate thesedrawbacks by also using the timing and character-identifying devices forregulating the speed of the DC motors.

BRIEF DESCRIPTION OF THE DRAWING The invention will be described withreference to the accompanying drawing, wherein:

FIG. I is a schematic block diagram of a printer and thespeed-regulating circuit of the invention; and

FIGS. 2 to 4 illustrate waveforms of voltages at different points in thespeed-regulating circuit of FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENT In FIG. 1, a regulating circuitin accordance with the invention, is employed with a serial printer. Forsimplicity, only the essential parts of the printer are shown. Thus, theprinter of FIG. 1 comprises a motor M which, through a shaft 1, drives atiming disk 2 and a type carrier 3 in continuous rotation. A pick up 4reads out appropriate marks carried by timing disk 2.

A print hammer 5, located proximate to type carrier 3, is actuated by anelectromagnet 6. A print-receiving member 7, usually of one or morepaper sheets, and an inking ribbon 8 are interposed between type carrier3 and print hammer 5.

Motor M, pick up 4, type carrier 3, timing disk 2, hammer 5, andelectromagnet 6 are mounted on two movable carriages, not shown, whichmove together in a direction perpendicular to the plane of the figure.

The signals delivered by pickup 4, are suitably amplified by I anamplifier 9 and applied to a pulse-squaring circuit 10, which can be asimple univibrator. The output of circuit 10 is a succession of squaretiming pulses of precise duration and am- ,plitude, having a repetitionrate depending on the number of marks located on timing disk 2 and onthe rotational speed of the disk. Under normal operating conditions,i.e., at constant speeds, this pulse repetition rate is constant.

As described in the above-mentioned patent application, the uniformsuccession of timing pulses may be interrupted by a relatively longinterval, due to the absence of a timing disk mark, or by two relativelyshort intervals, due to an additional interposed timing disk mark. Thisnonuniformity is provided to identify a predetermined angular positionof the type carrier, such as an initial position, and occurs once eachrevolution of the type carrier. However, as will be explainedhereinafter, despite these nonuniformities, the timing pulses providedby circuit 10 may be used to regulate the motor speed.

The output pulses of circuit 10 are applied to a logical counting andcomparing circuit 1 which, through an amplifi- 'er 1?. controls theenergizing of printing electromagnet 6 at known, on the supply frequencyand the number of poles of the proper times.

In accordance with the invention, the output timing pulses of circuit 10are also applied to a regulating circuit 25 for controlling andregulating the speed of motor M. In the preferred embodiment, circuit 25comprises a pair of monostable univibrators l3 and 14, a pair ofinverters l5 and I6 and a bistable circuit or flip-flop l7.

Univibrator 14 is preferably of the fast recovery type. Inverters l5 and16 introduce an appropriate delay in the pulses applied to the inputs 22and 23 of flip-flop 17. The output of flipflop 17 is applied to acontrollable power supply circuit l8,

which is adapted to deliver to motor M a first or a second level ofsupply voltage, according to the signals received by flip-flop Theoperation of regulating circuit 25 will now be explained with referenceto the waveforms of FIG. 2.

When motor M is started, a succession of timing pulses, having initiallya very low repetition rate due to the low speed of the motor, is appliedto the input of circuit 25, waveform a of FIG. 2.

The negative excursion of the first timing pulse 19 triggers thedelivery of a positive pulse 20 by univibrator l3, waveform b of FIG. 2.Timing pulse 19 is also applied to the clock input 21 of flip-flop l7and enables flip-flop 17 to assume a state corresponding to the signalsapplied to inputs 22 and 23 of the flipflop.

in its initial state, univibrator 14 is at rest. At the time when thefirst timing pulse 19 is applied to flip-flop 17, because of the delayintroduced by inverters l and 16, the signals applied to inputs 22 and23 continue to correspond to the initial state of univibrator 14, theoutput of flip-flop 17 does not change from its initial value, which isassumed to be at a relatively positive level. This positive level outputof flip-flop 17 controls power supply circuit 18 to supply motor M withfull voltage, which thereby delivering a torque sufficient for itsacceleration.

Univibrator 14, upon being actuated by the output pulse of univibrator13, generates a positive pulse of predetermined duration T waveform c ofFIG. 2, duration T being the characteristic time" of univibrator 14.However, this pulse of univibrator 14 is applied to flip-flop 17 onlyafter a predetermined delay relative to timing pulse 19, waveform d ofFIG. 2, and therefore, in the absence of a pulse on input 21, the stateof flip-flop 17 cannot change from its initial value, waveform e of FIG.2.

When the second timing pulse 24 is applied to circuit 25, univibrators13 and 14 and the output signals of inverters l5 and 16 have returned totheir rest conditions. Accordingly, although the sequence of actuationof both univibrators is repeated as before, the state of flip-flop 17remains unchanged.

In this condition motor M continues to accelerate. Finally, however,when the repetition period T of the timing pulses delivered by circuitbecomes equal to the predetermined duration T, which occurs when therequired motor speed is reached, fast recovery univibrator 14 isactuated before the termination of its preceding output pulse.Accordingly, when the next timing pulse is applied to flip-flop 17, thesignals applied to its inputs 22 and 23 are inverted with respect to therest condition of the circuit, waveform d of HG. 2. Flip-flop l7thereupon transfers to its opposite state, wherein its logical outputvalue is zero. This zero level controls power supply circuit 18 tosupply motor M with a reduced voltage, and that the motor deceleratesslightly. However, as soon as the repetition period T of the timingpulses again becomes slightly greater than predetermined duration T, theinitial sequence of operations is repeated and motor M is again suppliedwith full voltage.

By this regulation technique, which can be termed an On- Off method, theactual operating speed of the motor is maintained very close to thenominal operating speed represented by the characteristic time T ofunivibrator 14.

Other regulating techniques, for example a proportional scheme, may beemployed to attain a higher degree of regulating precision, withoutdeparting from the spirit and scope of the invention. The operation of aregulating circuit, such as the one disclosed, is not adversely affectedby the presence of an additional timing pulse or by the absence of atiming pulse once each revolution of the timing disk, either occurrencebeing employed to identify a predetermined position of the type carrier,in accordance with the teachings of the aforementioned patentapplication. The waveforms of FIGS. 3 and 4 illustrate the operation ofthe circuit under such circumstances.

FIG. 3 demonstrates the case of the additional timing pulse, which isused for identifying the initial position of the type carrier. Duringdeceleration of motor M the presence of an additional pulse has noeffect, inasmuch as it further reduces the preceding pulse is less thancharacteristic time T, this condition is interpreted by regulatingcircuit 25 as the attainment of the nominal operating speed and,consequently, the motor supply voltage is reduced. If the interval T' bywhich the next successive timing pulse follows the additional pulse isless than characteristic time T, the control condition of reducedvoltage is continued. However, the next successive timing pulse willoccur following an interval T, which is greater than time T, so that thefull supply voltage is restored. The disturbance of the regulatingoperation-is limited, therefore, to the span of two timing pulses,corresponding to two characters, and has no appreciable adverseinfluence on the actual operating speed of the motor.

Similar consideration also apply in the instance the absent timingpulse, although in this instance the nonuniformity participates duringdeceleration of motor M. Referring to FIG. 4, the absence of a timingpulse causes an interval T" between consecutive timing pulses greaterthan characteristic time T. This condition is interpreted by regulatingcircuit 25 as a decrease in operating speed and, consequently, at thenext timing pulse full supply voltage is delivered to the motor.However, this condition occurs only in the interval between the next twotiming pulses and is not of sufficient duration to sensibly acceleratethe motor.

The failure of these nonuniformities to adversely influence operation ofthe circuit is because the repetition period of the timing pulses isbetween about 500 psec. and 2 psec, whereas the repetition period of theadditional timing pulse, or missing timing pulse, depends on the numberof the characters in the set of characters, and is of a duration 10 ormore times the duration of the normal period.

Iclaim:

l. A high-speed printer of on-the-fly" type having symbols to be printedarranged on a type-carrying member, said member being maintained inmotion relative to a printing position by suitable motor means operatingat a predetermined speed, comprising in combination:

timing means for delivering a succession of pulses to denote theposition of the characters to be printed and the time for actuation ofthe print operation;

first circuit means responsive to said pulses to control said printingoperation; and

second circuit means responsive to said pulses to control the operatingspeed of said motor means, whereby both the timing of the printingoperation and the regulation of the operating speed of said motor meansare controlled by said pulses.

2. A high-speed printer as in claim 1, wherein said second circuit meanscomprises a fast recovery monostable univibra tor triggered in responseto said pulses to provide an output signal, a bistable element enabledfor triggering by said pulses and having set and reset inputs, saidoutput signal being applied in direct and inverted form to said set andreset inputs respectively, said bistable element providing an outputcontrol signal to control the operating speed of said motor means.

3. High-speed printing apparatus comprising:

an image-bearing member adapted for movement past a printing positionand bearing a plurality of different character images spaced apart onsaid member along said direction of movement,

a controllable driving member connected to drive said image-bearingmember past said printing position to carry said character imagessuccessively past said printing position,

printing apparatus disposed proximate to said printing position and,when actuated by an energizing signal, for cooperating with the one ofsaid character images at said printing position to make a copy of saidone image,

a timing indicia bearing member integrally associated with saidimageobearing member to move with said imagebearing member, said timingindicia bearing member comprising a timing indicium for each of saidcharacter images, each of said timing indicia being located on saidtiming indicia bearing member at a position corresponding to theposition of the respective one of said character images,

sensing means disposed for sensing the timing indicia on said timingindicia bearing member as said timing indicia move past said sensingmeans and for delivering a timing signal when each ofsaid timing indiciais sensed,

circuit means responsive to each of said timing signals and enabled whena copy is to be made of the respective one of said character images tosupply an energizing signal to said printing apparatus,

each one of said timing indicia being disposed on said timing indiciabearing member at a position to be sensed by said sensing means acharacteristic duration before the respective one of said characterimages reaches said printing position when said driving member isoperating at a predetermined speed, said characteristic durationcorresponding to the interval between the time when said one timingindicium is sensed by said sensing means and the time when said printingapparatus is ready to make a copy of the respective character image, andcontrol means responsive to said timing signals to control said drivingmember to maintain a substantially constant driving speed.

4. The apparatus of claim 3, wherein said control means responds to therate of recurrence of said timing signals to control said drivingmember.

5. The apparatus of claim 4, wherein said control means responds to arelatively low rate of recurrence for accelerating said driving memberand to a relatively high rate ofrecurrencc for decelerating said drivingmember.

6. The apparatus of claim 3, wherein said control means compares theintervals between successive ones of said timing signals with saidcharacteristic duration to control said driving member.

7. The apparatus of claim 6, wherein when said intervals are less thansaid characteristic duration said control means decelerates said drivingmember and when said intervals are greater than said characteristicduration said control means accelerates said driving member.

8. High-speed printing apparatus comprising:

an image-bearing member adapted for movement past a printing positionand bearing a plurality of different character images spaced apart onsaid member along said direction of movement,

a controllable driving member connected to drive said image-bearingmember past said printing position to carry said character imagessuccessively past said printing position,

printing apparatus disposed proximate to said printing position and,when actuated by an energizing signal, for cooperating with the one ofsaid character images at said printing position to make a copy of saidone image,

a timing indicia bearing member integrally associated with saidimage-bearing member to move with said imagebearing member, said timingindicia bearing member comprising a timing indicium for each of saidcharacter images, each of said timing indicia being located on saidtiming indicia bearing member at a position corresponding to theposition of the respective one of said character images,

sensing means disposed for sensing the timing indicia on said timingindicia bearing member as said timing indicia move past said sensingmeans and for delivering a timing signal when each of said timingindicia is sensed,

circuit means responsive to each of said timing signals and enabled whena copy is to be made of the respective of said character images tosupply an energizing signal to said printing apparatus, and

contro means responsive to the rate of recurrence of said timing signalsto control said driving member to maintain a substantially constantdriving speed.

9. The apparatus of claim 8, wherein said control means compares theintervals between successive ones of said timing signals with acharacteristic duration to control said driving member, saidcharacteristic duration corresponding to the interval between the timewhen one of said timing indicia is sensed by said sensing means and thetime when said printing apparatus is ready to make a copy of therespective character image.

10. The apparatus of claim 9, wherein said intervals are less than saidcharacteristic duration said control means decelerates said drivingmember and when said intervals are greater than said characteristicduration said control means accelerates said driving member.

UNITED STATES PATENT OFFICE CETIFICATE OF CEQTE 3 36 a Dated Januaw 45;1972 Patent No.

Inventor(s) Giorgio Bonzano It is certified that error appears in theabove-identified patent and that said Letters Patent are herebycorrected as shown below:

Column 6, line 27, after "respective" should read Signed and sealed this24th day of October 1972.

(SEAL) Attest:

EDWARD M.FLETCHER,JR. ROBERT Commissioner of Patents Attesting OfficerDRM Poqoso (10'69) USCOMM-DC 6O376-P6O u.s. GOVERNMENT FRINTING OFFICE:I969 0-566-334.

1. A high-speed printer of ''''on-the-fly'''' type having symbols to beprinted arranged on a type-carrying member, said member being maintainedin motion relative to a printing position by suitable motor meansoperating at a predetermined speed, comprising in combination: timingmeans for delivering a succession of pulses to denote the position ofthe characters to be printed and the time for actuation of the printoperation; first circuit means responsive to said pulses to control saidprinting operation; and second circuit means responsive to said pulsesto control the operating speed of said motor means, whereby both thetiming of the printing operation and the regulation of the operatingspeed of said motor means are controlled by said pulses.
 2. A high-speedprinter as in claim 1, wherein said second circuit means comprises afast recovery monostable univibrator triggered in response to saidpulses to provide an output signal, a bistable element enabled fortriggering by said pulses and having set and reset inputs, said outputsignal being applied in direct and inverted form to said set and resetinputs respectively, said bistable element providing an output controlsignal to control the operating speed of said motor means.
 3. High-speedprinting apparatus comprising: an image-bearing member adapted formovement past a printing position and bearing a plurality of differentcharacter images spaced apart on said member along said direction ofmovement, a controllable driving member connected to drive saidimage-bearing member past said printing position to carry said characterimages successively past said printing position, printing apparatusdisposed proximate to said printing position and, when actuated by anenergizing signal, for cooperating with the one of said character imagesat said printing position to make a copy of said one image, a timingindicia bearing member integrally associated with said image-bearingmember to move with said image-bearing member, said timing indiciabearing member comprising a timing indicium for each of said characterimages, each of said timing indicia being located on said timing indiciabearing member at a position corresponding to the position of therespective one of said character images, sensing means disposed forsensing the timing indicia on said timing indicia bearing member as saidtiming indicia move past said sensing means and for delivering a timingsignal when each of said timing indicia is sensed, circuit meansresponsive to each of said timing signals and enabled when a copy is tobe made of the respective one of said character images to supply anenergizing signal to said printing apparatus, each one of said timingindicia being disposed on said timing indicia bearing member at aposition to be sensed by said sensing means a characteristic durationbefore the respective one of said character images reaches said printingposition when said driving member is operating at a predetermined speed,said characteristic duration corresponding to the interval between thetime when said one timing indicium is sensed by said sensing means andthe time when said printing apparatus is ready to make a copy of therespective character image, and control means responsive to said timingsignals to control said driving member to maintain a substantiallyconstant driving speed.
 4. The apparatus of claim 3, wherein saidcontrol means responds to the rate of recurrence of said timing signalsto control said driving member.
 5. The apparatus of claim 4, whereinsaid control means responds to a relatively low rate of recurrence foraccelerating said driving member and to a relatively high rate ofrecurrence for decelerating said driving member.
 6. The apparatus ofclaim 3, wherein said control means compares the intervals betweensuccessive ones of said timing signals with said characteristic durationto control said driving member.
 7. The apparatus of claim 6, whereinwhen said intervals are less than said characteristic duration saidcontrol means decelerates said driving member and when said intervalsare greater than said characteristic duration said control meansaccelerates said driving member.
 8. High-speed printing apparatuscomprising: an image-bearing member adapted for movement past a printingposition and bearing a plurality of different character images spacedapart on said member along said direction of movement, a controllabledriving member connected to drive said image-bearing member past saidprinting position to carry said character images successively past saidprinting position, printing apparatus disposed proximate to saidprinting position and, when actuated by an energizing signal, forcooperating with the one of said character images at said printingposition to make a copy of said one image, a timing indicia bearingmember integrally associated with said image-bearing member to move withsaid image-bearing member, said timing indicia bearing member comprisinga timing indicium for each of said character images, each of said timingindicia being located on said timing indicia bearing member at aposition corresponding to the position of the respective one of saidcharacter images, sensing means disposed for sensing the timing indiciaon said timing indicia bearing member as said timing indicia move pastsaid sensing means and for delivering a timing signal when each of saidtiming indicia is sensed, circuit means responsive to each of saidtiming signals and enabled when a copy is to be made of the respectiveof said character images to supply an energizing signal to said printingapparatus, and control means responsive to the rate of recurrence ofsaid timing signals to control said driving member to maintain asubstantially constant driving speed.
 9. The apparatus of claim 8,wherein said control means compares the intervals between successiveones of said timing signals with a characteristic duration to controlsaid driving member, said characteristic duration corresponding to theinterval between the time when one of said timing indicia is sensed bysaid sensing means and the time when said printing apparatus is ready tomake a copy of the respective character image.
 10. The apparatus ofclaim 9, wherein said intervals are less than said characteristicduration said control means decelerates said driving member and whensaid intervals are greater than said characteristic duration saidcontrol means accelerates said driving member.